Compound hoist



May 25, 1943. E. R. BARRETT COMPOUND HOIST Filed Jan. 9-, 1941 '3 Sheet-Sheet 1 I May 25, 1943.

E. R. BARRETT COMPOUND HOIST Filed Jan. 9, 1941 3 Sheets-Sheet 2 23 I BY l2? INVENTOR ill'ddzzmfi ATT NEYS.

May 25, 1943. E. R. BARRETT COMPOUND HOLST Filed Jan. 9, 1941 3 Sheets-Sheet 3 INVENTOR Efiarreii.

g i ATI'O EY5- Patented May 25, 1943 COMPOUND HOIST Edward R. Barrett, Detroit, Mich, assignor to Gar Wood Industries, Inc., Detroit, Mich, a corporation of Michigan Application January 9, 1941, Serial N0. 373,763

9 Claims. (Cl. 298-22) The present invention relates to motor vehicles and particularly relates to improvements in hoist mechanisms for tilting a dump truck body about the chassis of a truck.

One of the primary objects of the present invention is to provide simplified and improved hoisting mechanism by which a high angle lift, or high angle of tilt, may be obtained by the use of simple elements which may be economically constructed and which are durable in the field and cost less to maintain than prior high lift mechanisms.

Another object of the invention is to provide improved hoisting mechanisms of the type mentioned which are adapted for commercial use over a wide range of loads, particularly on high angle lift trucks and which have sufllcient' leverage to obtain a high angle and at the same time overcome clearance dimculties on certain type of trucks.

Another object of the invention is to provide a novel auxiliary hoist mechanism.

Another object of the invention is to provide an improved dump body and hoist mounting in which the main hoist cylinder is mounted on the body hinge, thereby simplifying the construction.

A further object of the invention is to provide a compound hydraulic hoist mechanism in wh ch one of the hoists acts to tilt the body through the initial period and another of the hoists acts to tilt the body through the latter periods, thereby providing a high angle lift in a simplified and economical manner.

A-further object of the invention is to provide an improved hoist of the type mentioned which is easily adaptable for powering upwardly only or for powering both up and down.

Other objects of the invention will become apparent from the following specification, the drawings relating thereto and from the claims hereinafter set forth.

In the drawings, in,which like numerals are used to designate like parts in the several views throughout:

Figure l is a fragmentary, side eievational view, with parts in cross-section, of a tiltable dump body having hoist mechanism according to the present invention associated therewith;

Fig. 2 is a cross-sectional view, with parts in elevation, taken substantially along the line 22 of Fig. 1;

Fig. 3 is a cross-sectional view taken substantially along the line 3-3 of Fig. 1;

Fig. 4 is a cross-sectional view taken substantially along the line 4-4 of Fig. 1;

Fig. 5 is a cross-sectional view, with parts in elevation, taken substantially along the line 5-5 of Fig. 3;

Fig. 6 is a cross-sectional view taken substantially along the line 6--6 of Fig. 5;

Fig. 7 is a diagrammatic view of the hydraulic circuit employed with the construction of Figs. 1

through 6:

Fig. 8 is a fragmentary, cross-sectional view, with parts in elevation, of one end of the auxiliary hoist mechanism and showing a modified form thereof; and

Fig. 9 is a cross-sectional view taken substantially along the line 9--9 of Fig. 8.

In prior dump body constructions of the vehicle type in which a body is tiltably mounted upon a truck chassis and in which means are provided for hoisting the body to tilt it about its hinge points, it has been the practice when it is desired to have a high angle lift to use telescoping hydraulic hoists. Such hoists are expensive to construct and present large wear areas on the outer cylinders of the telescoping hoist sections so that when they are used in the field the maintenance cost is considerable. It will be appreciated that the reason for this is that the trucks are used under conditions in which a considerable amount of dust and dirt is deposited on the hoist cylinder walls so that as the cylinder sections are reciprocated to telescope in and out with respect to each other, the surfaces thereof become scored. Such hoists require constant attention and frequent repairs are necessary.

According to the present invention, a high angle lift is provided in a simplified manner in that the main hoist is of the piston and cylinder type and is operatively connected with the body through a linkage mechanism. The linkage mechanism includes an extensible link which is also of the piston and cylinder type of hydraulic jack. In this manner, standard parts may be used and such parts stand up well in use and do not require the attention and maintenance costs mentioned above.

Referring to the drawings, a dump truck is generally indicated at In and includes the usual chassis I2 having the cab and engine compartment (not shown) disposed adjacent the forward end thereof in the usual way. A dump body generally indicated at I4 is pivotally mounted with respect to the chassis about transversely aligned pivot pins It by means of depending brackets l8 thereof, Such pivot pins 16 7 provide the hinge point for the body; and, in the present invention, also provide the means for pivotally connecting one end of the main hydraulic jack to the chassis. as will be pointed out in more detail hereinafter.

The body is supported upon an auxiliary hoisting frame upon which the hoisting mechanism is mounted, and such auxiliary fram is mounted upon the truck chassis. The construction of the body, the auxiliary hoist frame and the chassis are similar to those disclosed in the United States Letters Patent of Edward R. Barrett, No. 2,234,135, granted March 4, 1941. In general, the body is formed with longitudinally extending members which are provided with inwardly directed, substantially horizontal flanges along the lower edge thereof. Transversely extending channel members are secured to the underside of the body and form part of the body frame at longitudinally spaced points.

The chassis l2 has a. unit, auxiliary hoisting frame of generally rectangular shape flxed thereto which includes longitudinally extending sill respect to the chasis is disposed under the bodyand is so constructed and arranged that it may be readily accommodated to the small space present under the body. g

The present invention is, in general, directed I which are transversely aligned and fixed to the underside of the body adjacent the rear end .4l which are in the form of elongated tubular to improvements over the hoisting mechanism disclosed and claimed. in the above mentioned Barrett patent, and has the advantages of such hoisting mechanism together with additional advantages which are present as a result of the present invention.

The hoisting mechanism of the present invention includes a power driven reciprocating element and a linkage means connecting the reciprocating element to the body, so that upon the power stroke of such element in one direction the body is caused to tilt upwardly about its pivots IS. The power means and the linkage means are so disposed that the power thrust of the power means is toward the front of the body or away from the pivots l6; and the linkage means are so constructed and arranged with respect to the chassis, bodyand power means that long lever arms and multiplied leverage are ;present in order to perform the hoisting or lifting operations of the truck body to dump the load.

The power means includes a hydraulic cylinder 29 having a cap 30 closing one end thereof and having the opposite end also closed. A piston 34 and piston rod 36 are disposed within the cylinder in the usual way and the piston rod slidably extends through an opening in the cap 30 and proiects therebeyond. Power for the cylinder isprovided by a gear pump 38, which is fixedly mounted with respect to thecylinder by means of a depending mounting bracket 39, or the like, and is connected through a flexible drive shaft 49 to a members rigidly connected tothe cylinder.

Such wings 4| are so arranged that they are generally triangular in form with the apices thereof extending toward the cap end of the cylinder 29 and connected at their base ends to transversely extending tubular members 42 which are rigidly secured to the base end of the cylinder 29. The tank members 4| communicate with the interior of the cylinder 29 through openings 43 formed in the cylinder wall and also communicate with the inlet of the pump through a passageway formed in mounting member 39 which is secured to one of the side wings 4|.

The members 42 form trunnions for pivotally mounting the cylinder 29 to the cha sis l2, and

' the outer ends of such members may be secured to the chassis l2 by means of brackets 44. The outer ends of members 42 pivotally receive therein the pivot pins It for pivotally mounting the body on the chassis so that a common hinge point for the body and the hydraulic jack is provided.

The forwardly projecting end of the piston rod 39 is fixedly connected to a T-connection 48 having laterally projecting portions 59 which are formed with end bearing portions. The end hearing portions provide pivots for pivotally connecting the piston rod to a pair of similar elements of the linkage means as will be pointed out in detail hereinafter.

The linkage means includes a pair of transversely spaced leverage members 54 which are formed of sheet metal stampings welded together to rovide a bell crank construction and which are connected for movement together by a transverse plate which is welded to both. The leverage members are formed with flanges along the edges thereof for the p se of strengthening and stiffening the same. Each of the members 54 is formed to provide an upstanding U-shaped pocket 56 along the rear edge thereof which is adapted to receive therein an extensible linkage member 58, which will be described in greater detail hereinafter.

The leverage member 54 is generally triangular in shape and is formed with a pivot bearing 69 at one comer thereof which receives a pivot pin 62. The pivot pin 62 extends transversely of the vehicle and is mounted within mounting brackets 64 which are mounted on the auxiliary frame unit 2|! so that the members 54 are pivotally mounted with respect to such auxiliary frame unit. The upper end-of each of the members 54 is formed with a pivot bearing 66 within which a transversely extending pivot pin 8 is disposed which extends through-the T-member 48 for pivotally connecting the piston rod 39 to the upper ends of the members 54. The lower end of each of the members 54 has a pivot pin 49 received therethrough which passes through pivot openings in the lower end of the extensible linkage members 59 for pivotally connecting such linkage members to the members 54. a

The general arrangement of the linkage means is preferably such as that disclosed in the above mentioned Barrett patent, particularly with respect to the relative positions of the pivot points above mentioned and also with respect to the direction of the power stroke of the hydraulic jack 2!.

The extensible linkage members 58 are in the power take-off of the engine. The usual control form ofhydraulic jacks and reference may be had to Figure 5 for a detailed description ofv such elements. The members 58 each includes a cylinder I8 having a cap end I2 and having the lower end I4 thereof closed and connected with an integral portion I8 which has a pivot opening therethrough for the reception of pivot pin 88.

A piston 18 is slidably disposed within the cylinder and is connected to apiston rod which slidably extends through a sealed opening in cap I2. The piston rod is formed of a pair of concentrically arranged tubular members 88 and 82 providing a central passage 84 and an annular passage 86 extending substantially the length of the piston rod. The member 88 extends through the piston 18 so that the passageway 84 communicateswith the interior of the cylinder toward the closed end I4 of the cylinder. A passageway 88 is provided through the member 82 on the opposite side of the piston I8 so that the passageway 86 is in communication with the interior of the cylinder on the opposite side of the piston I8 from that with which the passageway 84 communicates with the interior of the cylinder.

The members 88 and 82 of the piston rod are secured adjacent their outer ends to a header member 98. The header member 98 is provided with a transversely extending inlet passageway 92 therethrough which communicates with the inlet passageway 84; and is also provided with another transversely directed, separate outlet passageway 94 which communicates with passageway 88. A pair of adjacent by-pass ports 98 and 98 are formed through the cylinder 18 adjacent the cap end I2, and a cover member 99 is fixed to the outer surface of cylinder I8 and over-lies the openings 98 and 98 to provide a communicating passageway I8I therebetween. The function of the openings 96 and 98 of the passageway I8I will be described in detail hereinafter.

The member 98 has annular bearing rings I82 fixed to the outer ends thereof which are pivotally received within trunnions mounted within transversely aligned bearing brackets I84 secured to the underside of the body I4 for pivotally connecting the extensible link 58 to the body.

An inlet conduit I88 is connected through a suitable fitting with passageway 92; and an outlet conduit I88 is connected through a suitable fitting with passageway 94, It will be obvious that fluid under pressure is supplied to the inlet conduit I88 for extending the auxiliary jacks 58 and the fluid within the cylinder is exhausted through opening 88 into passageway 88 and then into the outlet conduit I88 through passageway 94. A flexible conduit II8 connects the outlet of the pump 38 with suitable lead con uits which communicate with the inlet of jacP-u 29 and 54 and also return conduits are provid d which lead to and communicate with the tank M.

Referring to Figure '7, the hydraulic circuit for operating the hoist ng mechanism is diagrammatically illustrated.

The pump 38 receives the fluid from the reserivoir or tanks 4| through conduit 39 and dis- ;f "charges such fluid through a pressure relief conareas of the pistons I8 of both of the jacks 58 so that while the fluid under pressure is present in all of the jacks, it is not effective to extend jacks 58 until jack 29 has been extended to its limit. Thus, the fluid under pressure enters jack 29 through inlet conduit H8 and extends. the piston rod 88 so that the leverage members 54 are pivoted about pivots 84 and the body is tilted about its hinge point I8 through the thrust on linkage members 58. When piston 34 has reached its limit of movement, the hydraulic pressure within inlet conduits I88 is then efl'ective to move pistons I8 to extend the piston rods thereof and further tilt the body.

The fluid from jack 29 is exhausted through conduit H8 and the fluid from jacks 58 is exhausted through conduits I88, all of which coinmunicate with a return conduit I28 which returns the fluid to the tank.

When the jacks 58 have been extended so that the piston I8 has been moved to the position shown in broken lines in Figure 5, the fluid passed into each of the cylinders I8 through conduit 84 by-passes' through passageway I8I around the piston and into passageway 88 for return to the tank as indicated by the broken line arrows in Figure 5.

With the construction above described, a high dump mechanism is provided which is simple in construction in that the body is first tilted a predetermined distance through the action of the hydraulic jack 29 alone and is thereafter further tilted by extending the extensible jacks 58. The body may be permitted to drop by gravity to its initial horizontal position.

If it is desired to power both up and down, the jacks 58 may be constructed to readily adapt themselves to this condition as well as to the powering up alone. A construction for so adapting the jacks 58 is shown in Figures 8 and 9. In such construction, an adapter plate I22 is welded to the outside of cylinder 18 over openings 98 and 98 and is formed with a tranverse recess portion I24 for providing communication between such openings. A closure plate I26 is removably secured to the adapter I22 by means of suitable screws I28 or the like. With the construction as shown in Figure 8, the operation may be the same as that described above in that the fluid may bypass around the piston through openings 95 and 98 If, however, it is desired to power down, the openings 98 and 95, which have been tapped. are readily adapted for the reception of pipe plugs (not shown) which may be used to close such openings. In order to insert such plugs, it is merely necessary to remove the cover plate I28.

The hoisting construction, including the leverage members and linkage members, has been illustrated here as having inboard mountings. that is, the leverage and linkage members are disposed inwardly of the chassis longitudinals. However, the structure of the present invention is just as adaptable to outboard mountings, that is, mountings in which the leverage and linkage members are disposed outwardly of the chassis longitudinals and are mounted on suitable outriggings. This outboard mounting is particularly useful in many cases because of interference with the leverage and linkage means due to the presence in a number of the present standard chassis of cross frame members.

Formal changes may be made in the embodiment of the invention illustrated and described without departing from the spirit and substance sis, a tiltable body, means pivotally connecting said body tosaid chassis, a hoisting device for tilting said body and having one end pivotally connected to said chassis and including an extensible power driven element, and means connecting said element withsaid body. said means including a transversely rigid, elongated and longitudinally extensible power element, and

means for extending said power driven element to tilt said body and thereafter extending the length of said extensible power element to further tilt said body.

2. Apparatus for tilting the body of a dump truck, comprising, in combination, a truck chassis, a tiltable body, means pivotally connecting said body to said chassis, a hoisting device for tilting said body and having one end pivotally connected to said chassis and including an extensible power driven element, and means connecting said element with said body, said means including a transversely rigid, elongated and iongitudinally extensible power element, and means for extending said power driven element to its full extent to tilt said body and thereafter extending the length of said extensible power element to further tilt said body.

3. Apparatus for tilting the body of a dump truck comprising, in combination, a truckchassis, a tiltable body, means pivotally connecting said body to said chassis, an hydraulic'jack for tilting said body and having one end pivotally connected to said chassis and including an extensible hydraulically actuated element, and means interposed between said element and said body and connecting said element with said body. said means including an auxiliary hydraulic lack, and means for extending said first named hydraulically actuated element to tilt said body and thereafter operating said auxiliary hydraulic jack to further tilt said body.

4. Apparatus for tilting the body of a dump truck comprising, in combination, a truck chassis, a tiltable body, means pivotally connecting said body to said chassis, a hoisting device having one end pivotally connected to said chassis and including a reciprocable power driven element, and means connecting said element with said body, said last named means including leverage means pivotally connected to said chassis, a

transversely rigid, elongated and longitudinally extensible power element having one end pivotally connected to said body and having the other end pivotally connected to said leverage means, mean pivotally connecting said extensible element to said leverage means, and means for ex-. tending said power driven elementto tilt said body and thereafter extending the length of said extensible element to further tilt said body.

'5. Apparatus for tilting the body of a dump truck, comprising, in combination, a truck chassis, a tiltable body, means pivotally connecting said body to said chassis, a hoisting device having one end pivotally connected to said chassis and including a reciprocable power driven element, and means connecting said element with said body, said last named means including leverage means pivotally connected to said chassis, linkage means of extensible length pivotally connected to said body, means pivotally connecting said linkage means and said leverage means together,

and means pivotally connecting said element to said leverage means, the arrangement of said element, said leverage means, said linkage means 5 and their respective connections with each other and with the point of pivotal connection of said body with the chassis being such that the power stroke of said element is away from the point of pivotal connection of said body with said chassis.

6. Apparatus for tilting the body of a dump truck, comprising, in combination, a truck chassis, a tiltable body, means pivotally connecting said body to said chassis, an hydraulic hoisting device having one end pivotally connected to said chassis and including an hydraulically actuated jack having a reciprocating ram, and means connecting said Jack with said body, said last named means including leverage means pivotally connected to .said chassis, an auxiliary hydraulic jack pivotally connected to said body, means pivotally connecting said auxiliary Jack and said leverage means together, and means pivotally connecting said ram to said leverage means, and means for hydraulically extending said ram to tilt said body and thereafter extending saidauxiliary hydraulic jack to further tilt said body.

7. Apparatus for tilting the body of a dump truck, comprising, in combination, a truck chassis, a tiltable body, means pivotally connecting said body to said chassis, an hydraulic hoisting device having one end pivotally connected to said chassis and including an hydraulically actuated jack having a reciprocating ram, and means connecting said jack with said body, said last named means including leverage means pivotally connected to said chassis, an auxiliary hydraulic Jack pivotally connected to said body, means pivotally connecting said auxiliary jack and said leverage means together, and means pivotally connecting said ram to said leverage means, and means for extending said ram to its full extent while said auxiliary hydraulic jack remains at its smallest length to tilt said body a predetermined distance, and thereafter extending the length of said auxiliary hydraulic Jack to further tilt said body.

8. Apparatus for moving a movable load carrying element comprising, in combination, a movable load carrying element, an hydraulic device for moving said element, said hydraulic device including an hydraulic Jack, means connecting said jack with said movable element, said lastnamed means including a transversely rigid, elongated and longitudinally extensible power element, and means for extending said extensible Dower element after said movable element has been initially moved a predetermined distance through actuation of said hydraulic jack.

9. Apparatus for moving a movable load carrying element comprising, in combination, a movable load carryingelement, an hydraulic device for moving said element, said hydraulic device including a first hydraulic jack, means interposed between said hydraulic Jack and said movable load carrying element connecting said jack with said movable load carrying element, said last named means including a second hydraulic jack, and means for extending said first named hydraulic Jack to its limit of movement to move said movable element and to thereafter initiate the movement of said second hydraulic Jack for furtltier moving said movable load carrying elemen EDWARD R. BARRETT. 

